A Universal Relation Database Interface for Knowledge Based Systems
Heikki Hyötyniemi, Aarno Lehtola · Database Systems for Advanced Applications · 1991
A universal relation query formalism (UQL) is presented and the transformation process from UQL into a standard relational database query language (SQL) is discussed. UQL has been designed to support knowledge based applications that need to access databases dynamically UQL hides details of the underlying relational database and offers means for achieving independence of the data representation. On the UQL level the target database is seen as a universal relation. Preserving the semantical meaning in the transformation from UQL to SQL is vital, no matter what the actual implementation of SQL is like. Finding a general mapping between these formalisms is the key topic in the paper. UQL query processing system has been tested as a part of a portable naZural language database interface.